(i) Field of the Invention
This invention relates to a meter for measuring erythrocyte settling rates.
(ii) Description of the Prior Art
Measurement of erythrocyte settling rates, usually described as a blood test, is one of the most common medical tests made. When pathogens are present, extra antibodies are secreted and carried in the blood. These are mainly proteins and they cause clumping of red blood cells into rouleaux which are larger than normal and hence settle faster. A blood test shows this, but such test, as presently operated, usually requires two hours for reliable results. In one standard form of blood test, a specific amount of anticoagulant must be used (to prevent clotting during the test) and, to ensure good mixing, a few minutes of shaking of the blood sample is required. Then a sample must be placed in a vertical rack, a timer set and the rate of sedimentation (3 mm/hour for healthy humans) observed for one to two hours. Usually the operation is done in a hospital or clinical laboratory. This generally means that with transportation delays, the results may not be known until the next day.
Other proposals have been made in analogous fields to determine settling rates for solids, or cloud points of liquids. In Canadian Pat. No. 715,290 issued Oct. 10, 1965 to P. G. Holdbourne, a method is provided for continuously monitoring the cloud point or the pour point of hydrocarbon oil, involving the use of a beam of light which is directed through the oil onto a reflecting surface. The temperature of the oil is measured when the intensity of the beam of light reflected from the reflecting surface decreases a predetermined amount.
Canadian Pat. No. 912,849 issued Aug. 10, 1972 to P. Cahour at al provides a device for controlling the rate of settlement of a solid in suspension in a liquid involving the use of a settlement cell comprising a vertical, transparent glass column, and a projector for projecting a horizontal beam of light through the column to be picked up by a photoelectric cell which can produce a signal that detects the precise moment when the settling face moves past that level.
U.S. Pat. No. 2,379,158 issued June 26, 1945 to P. R. Kallscher et al provides a technique for the determination of the characteristics of the particles in a powdered material using an apparatus including a vertically disposed settling column, a light source and a light sensitive device disposed about the settling column to indicate the relative light transmission through a cross-sectional portion of the column, the column being transparent at this point. The light source and light sensitive device are disposed at a sufficient distance from the admission end of the column so that the admitted particles of the powdered material, under the influence of settling forces, undergo a relative gradation resulting in closely similar sized particles being present in any cross-sectional volume of dispersing medium in the settling column when the particles settle past the portion through which light from the light source passes.
U.S. Pat. No. 2,514,260 issued July 4, 1950 to M. S. Rosen provides apparatus for determining the rate of sedimentation of the solid particles in a fluid menstruum, e.g., the erythrocyte sedimentation rate of any blood or fluid containing blood. The apparatus includes a container comprising two parallel circular discs connected at their peripheries by a cylindrical band. The container, when filled with blood, must be maintained vertical. A circular opening is located at one point on the band and a short tube is connected with the opening to facilitate filling of the space between the discs and the band. One face of the disc has indices thereon, to permit reading of volumes of sediment settling within the container. U.S. Pat. No. 2,528,704 issued Nov. 7, 1950 to P. M. Neuda provides apparatus for determination of the settling rate of erythrocytes. The erychrocyte settling container is of predetermined triangular vertical section which gradually widens from its top to the bottom. The container is disposed so that there is a vertical orientation go that a wide zone of separation of the fluid-solid mixture is provided at the bottom while, simultaneously, both a quick transfer of the plasma through narrowing spaces toward the surface and a subsequent speed sedimentation of the erythrocytes through spaces widening towards the bottom is secured.
U.S. Pat. No. 2,741,913 issued Apr. 17, 1956 to N. Dovau relates to improvements in racks for holding ungraduated sedimentation tubes against a graduated background. The patented rack is for holding sedimentation tubes beside graduated scales and comprises a body block member having bottom feet and a central portion supported by and bridging such feet, a front face and a plurality of spaced vertically oriented sedimentation tube openings adjacent the front face, a plurality of spaced graduated scales on the front face adjacent the openings, and a plurality of spring clips secured to the body block member and disposed in the openings removably to hold sedimentation tubes therein.
U.S. Pat. No. 3,009,352 issued Nov. 21, 1961 to P. M. Neuda provides an improvement in the Neuda triangle of U.S. Pat. No. 2,528,704. The new triangular container is a triangularly shaped flat container, the sides of the triangle being equilateral, with a top aperture, a V-shaped neck outside the triangle, with each side of the V being exactly parallel to the side of the triangle opposite thereof, and a precise scale, on the outside of the triangular container calibrated in desired units.
U.S. Pat. No. 3,411,352 issued Apr. 29, 1969 to L. A. Hughes provides a colorimeter which includes a plurality of photoelectric cells, each having associated with it a light filter which removes all except the particular monochromatic band of light to which the photoelectric cell is primarily responsive and where its peak response is located. Thus, a different cell is used for each colour of light. A receptacle receives a colorimeter cuvette containing a specimen, a spring in the cuvette urging it against one side thereof. At one side of the receptacle is an electric lamp as a light source and on the diametrically opposite side, against which the cuvette is urged, are a plurality of vertically displaced photoelectric cells. Each cell has maximum sensitivity to a different monochromatic light and has associated with it a filter for transmitting to the cell that monochromatic light to which its cell has maximum sensitivity. An electric circuit includes the lamp, switch means for placing each cell in the circuit, only one at any time, a bridge circuit responsive to the current of the cell then in the circuit, and an electrical heater which operates na incubator having a plurality of cuvette receptacles. A plurality of interchangeable meters, each relevant to one particular test and calibrated for direct reading in that test in conjunction with one cell and each insertable into and removable from the electric circuit is supplied, but only one is used at a time across the bridge circuit for measuring light transmissivity of the specimen as expressed by the current passing through the photoelectric cell then in the electric circuit. Some of these meters have an actuator and some do not, the actuator, when present, throwing the switch means to place a different cell in the electric circuit.
U.S. Pat. No. 3,812,966 issued May 28, 1979 to W. A. Beach et al provides a determination of the settling rate of particulate matter by passing a mixture of the fluid and the particulate matter through an inclined tube at a known flow rate within the laminar flow range. Lights are positioned on one side of the inclined tube, and photocells are positioned on the other side. The signals generated thereby may be used to control the operation of a separator.
U.S. Pat. No. 4,027,971 patented June 7, 1977 by P. Kolman et al provides an analytical apparatus for counting the quantity of blood cells, suspended in a predetermined quantity of blood fraction. White light, which is directly transmitted through a predetermined volume of the blood, is filtered through a light filter, and light of the selected optical wavelength is passed through.
U.S. Pat. No. 4,187,462 patented Feb. 5, 1980 by R. Haker et al provides a device for determining the blood sedimentation rate in a substantially vertical test tube. The electrical or magnetic property of a given volume of liquid, which is changed by the settling of the erythrocytes in the test tube is measured as a function of time, by electrical means.
German Offenlegungsschrift No. 2,324,015 published Nov. 28, 1974 provides a system for measuring the settling speed of erythrocytes in blood by resonant frequency measurement.
Finally, German Pat. No. 916,128 dated July 8, 1949 of J. Reppisch provides a blood test machine in which tubes containing blood are held in an inclined position, and in which the settling rate is estimated visually.